Xfce 4.6 is the current version in NetBSD. One of OpenBSD porters was, and I think still is, on the Xfce development team and had the huge task of working around the "linuxisms" that are finding their way into the latest Desktop environments.
Examples are the sound server: BSD uses sndio Xfce 4.6 used alsa or oss. Xfce 4.8 switched to gstreamer. Gnome has recently made pulseaudio a requirement. The OpenBSD developers had to "route" the output of these newer sound servers to sndio.

Other examples involve automounting devices in the respective filemangers (Thunar/Nautilus).

One of OpenBSD porters was, and I think still is, on the Xfce development team and had the huge task of working around the "linuxisms" that are finding their way into the latest Desktop environments.
Examples are the sound server: BSD uses sndio Xfce 4.6 used alsa or oss. Xfce 4.8 switched to gstreamer. Gnome has recently made pulseaudio a requirement. The OpenBSD developers had to "route" the output of these newer sound servers to sndio.

Other examples involve automounting devices in the respective filemangers (Thunar/Nautilus).

That person would be landry@ (he is both OpenBSD and Xfce upstream... as well as Mozilla upstream!)
I don't think the task, for Xfce, is anywhere near as "huge" as you make it sound. Not to say his work isn't appreciated, but Xfce is much better for portability than others.